The field of the invention relates to sensor arrays and techniques for the detection of analytes, and in a specific embodiment, electronic techniques and devices for olfaction.
Human beings have at least five sensesxe2x80x94sight, smell, taste, hearing, and touch. Since the earliest times, humankind has sought techniques and devices for enhancing and extending these senses. Many of the devices and instruments that have been developed to extend human perception are considered among of the most revolutionary inventions in history. These inventions have had a profound impact on human civilization and have led to many additional breakthroughs and discoveries. Just a few of the many instruments developed to extend the reach of human perception include the telescope, microscope, stethoscope, X-rays, phonograph/radio/audio amplifier, scanning electron microscope, night vision goggles, and many, many others.
As would be expected, there has been considerable interest in developing a device or instrument for the general detection of analytes in a fluid, vacuum, air, or other medium. A specific instance of an analyte detector is a device for sensing smell or odors (i.e., analytes in air). It is well recognized that some animals like dogs have a keener sense of smell than human beings. Because of their xe2x80x9cnoses,xe2x80x9d dogs have been utilized for many tasks including, for example, the detection of bombs, mines, drugs, poison gases, and illegal contraband; dogs also aid in the search and rescue of humans. Devices for sensing smell would be useful for the traditional applications where animals are used, as well as for a multitude of uses where animals are impractical or inappropriate.
Moreover, a device for the general detection of analytes has potentially many more applications than a specific device for detecting smells. For example, the uses for a device for analyte detection include the detection of chemical leaks, quality control in food processing, medical diagnosis and testing, fabrication and manufacture of commercial and industrial goods, pharmaceutical production, testing or evaluating any odorant or analyte in any medium (e.g., fuel, oil, wine, solvents), and many other applications. An instrument for analyte detection would be highly desirable in industries and applications such as the chemical and petrochemical sectors, food, fragrance, medical, automotive, military, environmental, health and safety, and indoor air quality. Therefore, it is desirable to develop techniques and devices for the detection of analytes.
An approach for sensing smells is to use surface acoustic wave (SAW) resonators. However, the signal transduction mechanism for SAW devices involves relatively complicated electronics, and are thus somewhat costly. Furthermore, SAW devices are generally extremely sensitive to both mass and acoustic impedance changes, and may not be suitable for use in all environments.
Therefore, there is a need for techniques and systems for analyte detection, especially ones that are low cost, easy to manufacture, provide rapid response, and produce accurate differentiation between different analytes and different concentrations of the same analyte.
The present invention provides techniques and a system for detecting and identifying analytes in fluids. The present invention also provides techniques for fabricating and manufacturing sensors to detect analytes in fluids. Analytes may include smells, tastes, vapors, odors, gases, liquids, and chemicals, among others. The fluid may be liquid or gaseous in nature. In the present invention, an analyte is sensed by sensors that output electrical signals in response to the analyte. The electrical signals may be preprocessed by filtering and amplification. This preprocessing may also include adapting the sensor and electronics to the environment in which the analyte exists. The electrical signals may be further processed to classify and identify the analyte.
There are many possible embodiments of an analyte detection system of the present invention. For example, the present invention may be used to implement an electronic olfaction system or xe2x80x9celectronic nose.xe2x80x9d Such a system may reveal the identification and concentration of vapors in a manner similar to the mammalian olfactory system. Another embodiment for the analyte detection system of the present invention may also be used to implement a device for tasting. This device would function similarly to a tongue. There are many other possible embodiments of the present invention, too numerous to name in this application.
In one embodiment, sensors of the present invention are fabricated using semiconductor processing techniques and formed on a single integrated circuit. The integrated circuit or chip may contain a plurality of sensors, each at a sensor site. The sensor sites are formed on a substrate such as silicon, and may be arranged in rows and columns. Structures or other means may be constructed on the substrate to constrain a sensor material at each sensor site. For example, the sensor sites may be a plurality of sensor wells that could hold the sensor material.
The sensor material applied to or formed at one sensor site may have a different composition from the sensor material at a different site. For example, each sensor in the analyte detection system may have a different composition from every other sensor. For example, the sensor material may consist of regions of a nonconductive organic insulating material and a conductive material such as carbon black; the composition of carbon black may vary for each sensor on the chip. By providing a system of diverse sensors, each sensor may have a different response characteristic for a given analyte.
The integrated circuit may also include an electrical connection at each sensor site to route the electrical signals from the sensor material to other circuitry. This circuitry may further process the electrical signals. The circuitry may be on the same chip (on-chip) with the sensors, or may be off the chip (off-chip) carrying the sensors, such as on a different integrated circuit. For example, an analyte detection system of the present invention may include two or more integrated circuits, making up an analyte detection chipset.
In a specific embodiment of the present invention, electronic circuitry resides on the same integrated circuit as the sensor site. In particular, there is circuitry associated with each sensor site, and this circuitry may be formed beneath or interspersed with the sensor sites.
The signals from the sensors may be further processed by classifying the response to the analyte. For example, each analyte may have a particular xe2x80x9cfingerprint.xe2x80x9d The analyte may be identified based on this fingerprint. The signal processing for the identification and classification of the analyte may be performed by on-chip or off-chip circuitry. For example, classification may be performed using a computer or other instrument, among other techniques. Therefore, using the techniques and system of the present invention, an analyte may be distinguished and identified.
An aspect of the present invention is the use of an array of sensors to detect analytes. A further aspect of the present invention is the use of an integrated circuit having an array of sensors to detect analytes. A still further aspect of the present invention is the use of a semiconductor process to fabricate an integrated circuit having an array of sensors for identifying an analyte.
In a specific embodiment, the present invention is an integrated circuit including a plurality of sensor sites formed on a semiconductor substrate, each sensor site for constraining the sensor material. The integrated circuit further includes an electrical terminal formed to measure an electrical property of the sensor material. The electrical property may be a resistance, capacitance, inductance, or other electrical property. The sensor material may be a material consisting of a nonconductive organic insulating material and a conductive material. The sensor site may be a sensor well.
In a further embodiment, the integrated circuit of the present invention includes an array of sensors for detecting chemical analytes, each sensor having a first and second output terminal. There are plurality of adaptive electronic circuits, each circuit associated with one of the sensors and coupled to the first and second output terminals of the associated sensor.
To fabricate a semiconductor structure, a plurality of layers are formed on a silicon substrate. A plurality of wells is created in the plurality of layers. The sensor material is deposited into each well. Further, the composition of the sensor material in each well may be different from the sensor material at another well on the silicon substrate.
Other objects, features, and advantages of the present invention will become apparent upon consideration of the following detailed description and the accompanying drawings, in which like reference designations represent like features throughout the figures.